Laser Imagesetter's Introduction

Laser imagesetter is to decompose the text into dot matrix by computer, and then control the laser scanning on the photosensitive film, and compose the text and image with the dot matrix of exposure points. It is at least five times more efficient than the old typography. Laser imagesetter is a kind of equipment developed in the 1970s. Laser imagesetter equipped with glass type library, using the main lens of different focal lengths on the imagesetter, can magnify or shrink the words on the glass type template, shoot into more than 20 kinds of different sizes of the words for imaging on the photographic plates.

Modern laser imagesetter are equipped with a microcomputer, the operator sits in front of the Chinese terminal, like the use of a typewriter, the use of computer editing and typesetting system, the manuscript into the computer. The contents of the manuscript are converted into dot matrix information by the computer, and the dot matrix information is used to control the acousto-optic modulator, so that the diffracted light passes through the beam expander and is reflected by the polyhedral mirror, and then the objective lens is focused on the photosensitive film into a spot with a certain size.

The main performance parameters of laser imagesetter are: recording accuracy (recording resolution), repeating accuracy (registration error), format, recording speed and laser wavelength, etc., among which recording accuracy and repeating accuracy are the two most important indicators to measure the performance of the imagesetter, and also the standard for dividing the grade of the imagesetter. The laser commonly used in the imagesetter is a helium-neon laser with a wavelength of 635nm red semiconductor laser, 650nm semiconductor laser and a wavelength of 780nm infrared light. The laser wavelength determines the type of film used and even the price of the film used. For example, domestic ammonia neon laser phototypesetting is the cheapest, almost all text phototypesetting are used this kind of film, and infrared phototypesetting film is expensive, less used.